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**Course Name : DESIGN OF MACHINE ELEMENTS**

Lecture #9 Pulley Recitation Course Name : DESIGN OF MACHINE ELEMENTS Course Number: MET 214

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**The shaft is driven at a uniform speed by pulley C**

The shaft is driven at a uniform speed by pulley C. The shaft in turn drives pulley B & D. The diameter of pulleys B, C,D are 10 in, 12 in, 14 in respectively. Belt tensions are shown. The diameter of the shaft is 1 1/2inches. a) Calculate Belt tension F3. b) draw torque diagram starting from A and preceding to E. c) calculate max shear stress due to torsion d) determine total bearing reactions at A & E e) draw shear and moment diagrams in horizontal & vertical lanes. f) sketch composite moment diagram g) determine 𝜎 𝑚𝑎𝑥 due to bending. h) Calculate using the 1927 shaft standard

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Problem #2 Given the information below and/or the information provided on problem #2 shown in the preceding diagram which includes pulley diameters, etc, find the quantities requested. Assume pulley D, when viewed from the end of shaft 2 looking toward load A, is rotating clockwise. HP of load A=5 HP Speed of shaft 2, n2=150 rpm a) Find torque associated with pulley D, i.e. TD= b) Find torque associated with pulley B, i.e. TB= c) Find speed of rotation of motor shaft, (rpm) i.e. find n1= d) Find speed of rotation of shaft #3, i.e. n3=

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Problem #2 continued: Assuming Tc=2000 in-lb e) Find torque associated with pulley A i.e. TA= f) Find motor torque TM= g) Find motor horse power HPm=

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h) Identify on drawing of problem #2 the direction of rotation of each pulley in the system. i) Given the FBD for the motor shaft and the axes for a torque diagram provided below, show all torques applied to the shaft and draw a torque diagram for the shaft on the axes provided

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**Example 2-8 : The carbon – steel countershaft shown in Fig**

Example 2-8 : The carbon – steel countershaft shown in Fig is 25 mm in diameter and supports two V-belt pulleys. The countershaft runs at 1100 rpm. The belt tension on the slack side of pulley A is 15 percent of the tension on the tight side. Assume the shaft has a uniform diameter of 25mm. Assume pulley labeled with letters C & D is a driven pulley transferring power to the shaft. a) What amount of torque is transferred by the shaft between the pulleys? b) draw a torque diagram c) Compute the angle of twist of the shaft between the two pulleys as a function of G. d) Find the maximum torsional shear stress in the shaft e) additional questions appear on next page

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f) For the system shown, determine total bearing reactions at both bearings. g) Determine the maximum amount of bending moment existing in the shaft.

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